Several patents disclose various nozzle type liquid jet devices, which are described hereinafter.
U.S. Pat. No. 7,100,846 (Pein) discloses a water-jet device for separating a biological structure. The separating nozzle is furnished with a nozzle channel, with the nozzle channel provided with one or several twisted grooves at the circumference of the nozzle channel and wherein the number of the twisted grooves and the diameter and the length of the nozzle channel are placed in such ratio that the separating jet subjected to pressure is rotated.
U.S. Pat. No. 5,037,431 (Summers et al) discloses a hand-held surgical apparatus with supporting equipment comprising a mechanism for producing a pressurized jet of fluid which is sufficiently energetic to fragment diseased human and animal tissue without damaging adjacent healthy tissue. Preferably the apparatus includes a jet of fluid which impinges obliquely onto the operative area such that diseased tissue underneath overlying healthy tissue may be fragmented, especially finger-like extensions from tumorous growths of the skin. The jet rotated about a generally vertical axis such that the points of impact of the water from the jet upon the operative area describe circular patterns, thereby effectively and quickly distributing fragmenting energy over a wide operative area. A supporting vacuuming apparatus for aspirating effluent or expended fluid and fragmented tissue from the operative site. A surgical procedure for removing tumorous growths at the cutaneous surface includes the steps of impinging a growth on the skin with a jet of pressurized fluid using the apparatus.
U.S. Pat. No. 6,029,912 (Woolley) discloses a device for producing a stream of aerated water, the device having a first opening for producing a first jet of water and a second opening for producing a second jet of water directed into the first jet of water so as to form a single turbulent stream of water in which air is entrained. The device being constructed by forming two relatively angled surfaces on at least one component, the surfaces having respective aligned grooves, forming two oppositely angled surfaces on at least one other component and mounting the two relatively angled surfaces against the two oppositely angled surfaces such that the grooves, together with the oppositely angled surfaces define passages for the formation of jets of water.
A disadvantage associated with the above mentioned devices and methods is their inability to produce a sterile jet with a diameter in the micrometer range.
Laser induced micro-flows in liquids partially overcome this problem.
Previous studies and investigations show that focusing a laser beam inside a liquid may lead to emission of gas bubbles and micro flows of liquid originating at the focal point of the laser beam. These bubbles and micro flows are typically generated in an irregular and uncontrolled manner.
When high power laser radiation is tightly focused inside liquid, it generates hot plasma assisted by the formation of shock wave and gas bubbles (i.e., cavitation bubbles) with various diameters, emitted from the focal point. The breakdown is initiated by multiphoton or avalanche ionization of molecules of the liquid.
The phenomenon of bubbles and micro flows formation by laser radiation focused in the liquid volume was used by various investigators including Song et al (U.S. Pat. No. 6,777,642) who discloses an apparatus and a method for producing a relatively sterile jet and E. A. Brujan et al, “Dynamics of laser-induced cavitation bubbles near elastic boundaries: influence of the elastic modulus”, Journ. of Fluid Mech., 433, p. 283, 2001, who investigated the interaction of a single laser-induced cavitation bubble with an elastic boundary experimentally by high-speed photography and acoustic measurements.
Song et al discloses a laser-based apparatus and method for cleaning solid surfaces immersed in liquids. Such solids include a Si substrate, a disk or a magnetic head slider where contaminants, including organic contaminants, especially particles in the micron or sub-micron scale are effectively removed from the solid surfaces.
Song et al. achieve this by generating a strong laser-induced liquid jet and shock wave near the solid surfaces immersed in liquid. The liquid is a solution of water and other solvents to help reduce adhesion force and enhance cleaning efficiency.
Thus, Song et al allow the creation of a relatively sterile jet. However, the apparatus and method of Song et al. fail to create a jet with a diameter in the micrometer range.
Similarly, E. A. Brujan et al were limited to use single nanosecond laser pulses in their investigations of laser induced breakdown in liquids.
Since jets induced by high repetition rate laser pulses as well as jets which are sterile and at the same time possessing a diameter in the micrometer range are highly desired and would be a great asset to the medical and biological fields, an aim of the present invention is to provide an apparatus and a method for creating a sterile jet with a diameter in the micrometer range or smaller which is induced by high repetition rate laser pulses.
Other advantages and aims of the present invention will become apparent after reading the present invention and reviewing the accompanying figures.